1. Field of the Invention
Exemplary aspects of the present invention generally relate to an optical scanning device, and more particularly, to a multi-beam scanning device using multiple light beams and an image forming apparatus that includes the multi-beam scanning device.
2. Description of the Background Art
Conventionally, there is known a single-beam optical scanning device employed in, but not limited to, an image forming apparatus, such as a digital copier and a laser printer. In order to increase recording speed of such single-beam optical scanning device, a rotation speed of a deflector, for example, a polygon mirror, is increased.
However, there is a drawback to this approach in that stress on a motor that drives the polygon mirror increases, thereby degrading its durability and generating noise and vibrations. Thus, there is a certain limit to the rotation speed of the polygon mirror.
In view of the above, multi-beam scanning devices that simultaneously emit a plurality of light beams so as to be able to simultaneously record multiple lines of an image, text, etc. have been proposed.
In such multi-beam scanning devices, since a plurality of light beams is emitted, it is necessary to properly adjust beam pitches in a sub-scan direction on a scanned surface so as to achieve a desired writing density or pixel density.
In order to achieve the desired writing density, the configuration of a device for adjusting the beam pitch of the related-art multi-beam scanning devices tends to be complicated, thereby increasing the size of the device and thus defeating the purpose of reducing the size of the image forming apparatus as a whole.
When the beam pitch is not properly adjusted, a desired image cannot be produced, resulting in performance failure of the image forming apparatus and reducing productivity.